Global Shutter Image Sensor Storage Shielding Layout

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing image sensors with global shutters face challenges in efficiently capturing fast-moving objects due to limitations in the design and manufacturing of storage devices within the pixel units.

Innovation Solution

The proposed image sensor design includes a storage device with a memory element, a first dielectric layer, and a light shielding element, where the light shielding element is electrically isolated from the memory element and overlapped with the perimeter of the storage transistor gate, enhancing the isolation and shielding of the storage device from incident light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the storage device is placed within the pixel unit without additional shielding, then the device complexity is reduced, but the stored image charges are damaged by incident light

Engineering Contradiction:

Improveprotection of stored image chargesVSAvoidstructure of storage device

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A light shielding element is introduced as an intermediary component between the incident light and the storage device. This element selectively blocks harmful light from reaching the stored image charges while allowing necessary optical paths to remain functional. The shielding element is positioned adjacent to the storage device and extends into the pixel unit, creating a protective barrier without requiring complete restructuring of the pixel architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light shielding element is divided into multiple portions: a first portion adjacent to the storage device and a second portion extending into the pixel unit. This segmentation allows the shielding function to be distributed across different spatial zones, providing targeted protection where needed while minimizing overall structural complexity and maintaining compatibility with existing pixel unit layouts.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the light shielding element is electrically connected to the memory element, then the shielding effect is enhanced, but the reliability decreases due to potential electrical interference

Engineering Contradiction:

Improveprotection of stored image chargesVSAvoidelectrical interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The electrical connection between the light shielding element and the memory element is deliberately removed. The shielding element operates independently without electrical coupling to the memory element, thereby eliminating potential sources of electrical interference such as noise coupling or cross-talk. The shielding function is achieved purely through spatial positioning and physical blocking rather than electrical mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the light shielding element overlaps extensively with the storage transistor gate, then the shielding effect is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improveshielding effectivenessVSAvoidalignment of light shielding element

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The light shielding element is designed to overlap with at least a portion of the storage transistor gate, providing sufficient shielding coverage without requiring complete overlap. This partial action approach achieves adequate protection of the stored image charges while reducing the stringency of alignment requirements during manufacturing, making the design more tolerant of normal fabrication variations.

Inventive Principle:

Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design improves the ability to capture accurate image data by effectively shielding the storage device from incident light, thereby preventing damage to stored image charges and ensuring reliable image capture.

Implementation Method 1

the light shielding element is overlapped with at least a part of a perimeter of the storage transistor gate in a vertical projection on a plane along a stacking direction of the memory element and the light shielding element

Methodology Applied

Scientific EffectLight blocking/shielding: Absorption (EM radiation)

Data Source

PatentUS12288794B2Image sensor and manufacturing method thereof

Publication Date: 2025.04.29 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An image sensor includes a storage device, where the storage device includes a memory element, a first dielectric layer and a light shielding element. The memory element includes a storage node and a storage transistor gate, where the storage transistor gate is located over the storage node. The first dielectric layer is located over a portion of the storage transistor gate. The light shielding element is located on the first dielectric layer and includes a semiconductor layer. The semiconductor layer is electrically isolated from the memory element, where the light shielding element is overlapped with at least a part of a perimeter of the storage transistor gate in a vertical projection on a plane along a stacking direction of the memory element and the light shielding element, and the stacking direction is normal to the plane.